This invention relates to methods for modifying the motion of an output-varying control element of, for example, a motor vehicle engine, wherein the position of a gas pedal is detected and a parameter is produced for controlling an output-varying control element as a function of the position of the gas pedal. The output-varying control may, for example, be a throttle flap in an intake duct or it may be a servo device controlling the fuel flow rate.
When the motion of an output-varying control element is modified proportionally to the actuation of the gas pedal by the operator of a motor vehicle, the problem arises that, if the opening of the throttle flap, for example, is too rapid, combustion of fuel in the combustion chamber of the engine will be incomplete. This leads in turn to increased emission of pollutants and to unnecessarily high fuel consumption. On the other hand, in certain cases if the response of the output-dependent control element is too slow a jerky increase or reduction in the output of the engine may be produced, with an adverse effect on riding comfort.
To solve this problem, German Offenlegungsschrift No. 41 08 956 describes a device for retarding the motion of an output-varying control element in which the gas pedal and the output-varying control element, i.e., a throttle flap or servo element controlling the fuel flow rate, are coupled by a pressure device which retards the motion of the control element relative to the actuation of the gas pedal.
The pressure device includes a cylinder housing connected to the gas pedal and a piston guided in the cylinder and connected to the throttle flap. The pressure chamber so formed communicates with the negative pressure in the intake duct behind the throttle flap and also with the ambient pressure through an adjustable restricted opening.
When the vehicle is accelerated by moving the gas pedal, the negative pressure in the pressure chamber is reduced by the cylinder motion and, as equilibrium is reached between the intake duct pressure and ambient pressure supplied through the restricted opening, the piston element will follow the cylinder motion, so that the throttle flap opens completely.
Beside having the disadvantage of a mechanical structure requiring additional space, this arrangement does not provide for adjustment of the retardation of the control element motion as a function of other parameters of the engine. It is doubtful also whether a controlled proportioning of fuel to obtain a stoichiometric fuel-air ratio is possible with such an adjustment of the intake air supply.